The present invention relates to a cleaning system to clean an image bearing member used in electrophotographic process and an image forming system equipped with said cleaning system.
In the field of image forming technology where images are formed by an electrophotographic system, efforts have been made in recent years to reduce toner particle size, thereby improving image quality. Resolution can be improved and sharp images can be formed by reducing toner particle size. However, the following problems arise in the cleaning process:
With the reduced size of toner particles, there is an apparent increase in adhesion of toner to the image bearing member. This makes it difficult to clean the image bearing member by removing it from the toner remaining after transfer. When using the cleaning method of using only the cleaning blade, cleaning failure occurs to deteriorate image quality. Especially when image is formed using the toner whose particles are formed by emulsion polymerization method or suspension polymerization method, cleaning failure called xe2x80x9csneaking-throughxe2x80x9d occurs, wherein remaining toner on the image bearing member passes through the cleaning system without being scraped off by the cleaning blade of the cleaning system. This is because the particle size is very small and toner particles are roughly spherical in shape.
Study is currently under way in an effort to solve the problem resulting from the reduced particle size of such toner particles. For example, Official Gazette of Japanese Patent Laid-Open NO.52808/1999 proposes the cleaning technology wherein conductive or semiconductive rubber is used as the material constituting the cleaning blade, and voltage having polarity reverse to that of toner is applied to the cleaning blade, thereby applying mechanical and electrical removing force to toner remaining on the image bearing member.
Official Gazette of Japanese Patent Laid-Open NO.189675/1991 discloses a cleaning technology which permits cleaning by installing a cleaning brush to apply electrostatic force and a cleaning blade to apply mechanical cleaning force on the downstream side of said cleaning brush.
In the image forming system based on electrophotographic method so far, a cleaning method using an elastic cleaning blade is known as a means of cleaning toner remaining on the image bearing member. This is extensively use for simple structure and lower cost.
In addition to cleaning of the toner after transfer, an image bearing member cleaning means is used to clean the surface of the image bearing member with a great deal of toner remaining thereon without being transferred, for example, after sudden suspension of the operation due to paper jamming or the like or on the patch created for image adjustment or the like.
When pulverized toner created by the conventional pulverization method is used, toner has been successfully scraped off for a long time without cleaning failure, even if a great deal of toner has reached the cleaning blade without being transferred.
In the image forming system based on electrophotographic method, many proposals have been put forth regarding the cleaning system laid out on the periphery of the carrier to clean the surface of the image bearing member.
In the normal image forming process, electrostatic latent image is formed on the image bearing member. After that, said electrostatic latent image is developed by toner to create a toner image. After said toner image is transferred, paper powder adhering to said carrier surface or remaining toner having failed to be transferred is removed by the cleaning system.
Amorphous toner produced according to the conventional pulverization method (average circularity of 0.95 or less) has been sufficiently scraped off only when the end of an elastic plate member called a cleaning blade is brought into mechanical contact with the surface of the image bearing member to scrape it off.
Said conventional cleaning technology, however, has the following problems:
(1) Sufficient cleaning cannot be performed when the potential distribution on the image bearing member is not uniform.
(2) If high voltage is applied to the cleaning blade for cleaning work, electric discharge or injection of electric charge into the image bearing member takes place. This results in image quality or image bearing member.
(3) Toner electrostatically attached to the cleaning blade is deposited with time, and deposited toner falls down to contaminate the image or interior of the equipment.
(4) If bias voltage applied to the cleaning roller in order to raise the cleaning performance of said cleaning roller, toner is absent between the downstream cleaning blade and image bearing member. This will deteriorate friction reducing effect by toner, and is likely to cause separation of the cleaning blade.
The cleaning system disclosed in said Official Gazette allows the cleaning function to be shared between a cleaning brush and cleaning blade, thereby ensuring improved cleaning performance. However, it has the following problems:
(5) Since the greater part of toner is removed by the brush located on the upstream side, the amount of toner between the toner carrier and cleaning blade can be very small. If this occurs, friction between the image bearing member and cleaning blade will be increased. This is likely to cause chattering where the cleaning blade vibrates, or curling where the cleaning blade tip rotates in the reverse direction following the image bearing member.
(6) According to an example disclosed in the Official Gazette of Japanese Patent Laid-Open NO.189675/1991, a high voltage is applied to the upstream brush roller and the image forming surface is likely to be damaged by electrical discharge. Especially in the initial phase of development, foreign substances (carrier in the developer, magnetic substance and mixed metal chip) are likely to deposit on an image former due to overshooting of the development bias. If a brush charged with said voltage is brought in contact with that portion, electric discharge will easily occur with the result that the image former is damaged and image failure occurs.
(7) In the real-world usage, toner deposits over the range in excess of the image forming area by scatters from the development device. When the disclosed art alone is used, it may be difficult to recover the toner having dispersed over said range. A simple countermeasure is to increase the width of the cleaning brush (roller). In this case, electric discharge occurs from the cleaning brush (roller) to which bias is applied to the substrate (aluminum used normally) of both image forming ends. This makes it difficult to maintain stable cleaning performances.
(8) In keeping with improvement of image quality in an image forming system, roughly spherical and small-sized toner is coming into use. Roughly spherical shape of toner is effective in increasing the development quality. Small-sized toner is essential to formation of a high resolution image. If the weight mean particle size is below 3 microns, however, deposition of toner on the image bearing member is caused by van der Waals force, with the result that fogging is produced to deteriorate image quality.
(9) Said roughly spherical and small-sized toner can be obtained with relative ease if it is made into polymerized toner (to be discussed later). Polymerized toner is preferably used to ensure high quality image. It is known in the related art that, when such polymerized toner is used, however, it is difficult to scrape said toner off the surface of the image bearing member with the cleaning blade as a cleaning means if much toner remains on the image bearing member.
(10) This is commonly explained by the following argument: The tip of said cleaning blade in contact with the image bearing member surface is vibrated by the rotation of the image bearing member, and a gap is produced between the tip of said cleaning blade and image bearing member surface due to said vibration. Since the polymerized toner is roughly spherical, it easily escapes through the above gap. This phenomenon tends to occur more frequently if the cleaning blade is used for a long time and friction of blade edge proceeds. Then cleaning failure is more likely to take place.
(11) For the reasons discussed above, there has been a problem of incomplete cleaning when a great deal of said toner without being transferred has arrived and the number of printings has increased.
(12) In response to the requirements for higher image quality in recent years, small sized roughly spherical polymerized toner with high mean circularity has come into use. Such polymerized toner with high mean circularity raises no problem when the cleaning blade has been replaced with a new one. In time it will gradually wears out resulting in poor contact with image bearing member. If contact pressure between cleaning blade and image bearing member is deteriorated, toner is considered to slip easily through the slight gap between the tip of the cleaning blade and the surface of the image bearing member, because of spherical shape of the toner particle. It can also be considered that both the shape and particle size are uniform and there is an increased affinity between toner particles with respect to the image bearing member.
(13) Toner with a high mean circularity is desired to be used to ensure high image quality. However, if cleaning of the image bearing member is not satisfactory, attached paper powder and remaining toner will adversely affect the formation of the next image, with the result that image quality is deteriorated.
The object of the present invention is to solve the problems in conventional cleaning technologies as indicated above.
Accordingly, to overcome the cited shortcomings, the object of the present invention can be attained by a cleaning apparatus described as follows.
1. A cleaning apparatus, comprising; a cleaning roller being either conductive or semi-conductive and in contact with an image bearing member carrying charged toner; a constant current source to apply a bias voltage, having a polarity opposite to that of toner utilized for a developing operation performed on the image bearing member, onto the cleaning roller; and a cleaning blade contacting the image bearing member and located at a downstream side of the cleaning roller in a moving direction of the image bearing member.
2. The cleaning apparatus of item 1, wherein the cleaning roller rotates in such a manner that its contact surface moves in the same direction as the moving direction of the image bearing member at a position in contact with the image bearing member, and the ratio between a roller moving velocity of the cleaning roller and a moving velocity of the image bearing member at the contact surface is within a range of 0.5:1 to 2:1.
3. The cleaning apparatus of item 1, further comprising: a removing member for removing toner from the cleaning roller by contacting the cleaning roller.
4. The cleaning apparatus of item 1, wherein the cleaning blade contacts the image bearing member with a pressing load being within a range of 1 to 30 grams/cm.
5. The cleaning apparatus of item 1, wherein the contact angle between the image bearing member and the cleaning blade is within a range of 0 to 40 deg.
6. The cleaning apparatus of item 1, wherein the hardness of the cleaning blade is within a range of 20 to 90 deg.
7. The cleaning apparatus of item 1, further comprising: a control section to control the constant current source so as to increase an absolute value of an electronic current applied by the constant current source according as an increase of an image-forming amount.
8. The cleaning apparatus of item 7, wherein the image-forming amount is a number of sheets on which images are formed.
9. The cleaning apparatus of item 1, further comprising: a control section to control the constant current source so as to increase an absolute value of a toner-collecting voltage applied by the constant current source according as an increase of an image-forming amount, wherein the toner-collecting voltage is equivalent to the bias voltage.
10. The cleaning apparatus of item 9, wherein the image-forming amount is a number of sheets on which images are formed.
11. The cleaning apparatus of item 1, further comprising: a control section to control the constant current source so as to apply either a toner-collecting voltage or a toner-releasing voltage onto the cleaning roller by selecting one of them in a time-sharing manner, wherein both the toner-collecting voltage and the toner-releasing voltage are equivalent to the bias voltage.
12. The cleaning apparatus of item 11, wherein the toner-releasing voltage is applied at every completion of forming images on a predetermined number of sheets.
13. The cleaning apparatus of item 12, wherein the predetermined number of sheets changes corresponding to a total number of sheets on which images are formed.
14. The cleaning apparatus of item 13, wherein the toner-releasing voltage is generated by superimposing an alternative current voltage on a direct current voltage.
15. The cleaning apparatus of item 1, further comprising: a control section to control the constant current source so as to increase an absolute value of a toner-collecting voltage according as an increase of an image-forming amount, and so as to apply either the toner-collecting voltage or a toner-releasing voltage onto the cleaning roller by selecting one of them in a time-sharing manner, wherein both the toner-collecting voltage and the toner-releasing voltage are equivalent to the bias voltage.
16. The cleaning apparatus of item 15, wherein the image-forming amount is a number of sheets on which images are formed.
17. The cleaning apparatus of item 15, wherein the toner-releasing voltage is applied at every completion of forming images on a predetermined number of sheets.
18. The cleaning apparatus of item 17, wherein the predetermined number of sheets changes corresponding to a total number of sheets on which images are formed.
19. The cleaning apparatus of item 17, wherein the toner-releasing voltage is generated by superimposing an alternative current voltage on a direct current voltage.
20. The cleaning apparatus of item 9, wherein the cleaning roller rotates in such a manner that its contact surface moves in the same direction as the moving direction of the image bearing member at a position in contact with the image bearing member, and the ratio between a roller moving velocity of the cleaning roller and a moving velocity of the image bearing member at the contact surface is within a range of 0.5:1 to 2:1.
21. The cleaning apparatus of item 9, further comprising: a removing member for removing toner from the cleaning roller by contacting the cleaning roller.
22. The cleaning apparatus of item 1, wherein an average circularity of toner particles included in the toner is within a range of 0.96 to 0.99, and a toner deposit amount per unit area on a surface of the image bearing member is not greater than 0.25 mg/cm2 at a surface area ranging from a first position at which the image bearing member contacts the cleaning roller to a second position at which the image bearing member contacts the cleaning blade.
23. The cleaning apparatus of item 1, wherein an average circularity of toner particles included in the toner is not smaller than 0.96.
24. The cleaning apparatus of item 23, wherein the cleaning roller is an elastic roller.
25. A cleaning apparatus, comprising: a cleaning roller being either conductive or semi-conductive and in contact with an image bearing member carrying toner; an electric-power source to apply a toner-collecting voltage and a toner-releasing voltage onto the cleaning roller; a control section to control the electric-power source; and a cleaning blade contacting the image bearing member and located at a downstream side of the cleaning roller in a moving direction of the image bearing member, wherein the control section controls the electric-power source so as to apply either the toner-collecting voltage or a toner-releasing voltage onto the cleaning roller by selecting one of them in a time-sharing manner.
26. An image-forming apparatus, comprising: an image bearing member; a developing device; and the cleaning apparatus cited in item 1.
27. The image-forming apparatus of item 26, wherein the image bearing member is an organic photoreceptor.
28. The image-forming apparatus of item 26, wherein the developing device performs a developing operation by employing toner particles formed by a polymerization method, in which a volume average particle size of the toner particles is within a range of 3.0 to 8.5 microns.
29. The image-forming apparatus of item 26, wherein the cleaning apparatus comprises: a control section to control the constant current source so as to increase an absolute value of a toner-collecting voltage according as an increase of an image-forming amount, wherein the toner-collecting voltage is equivalent to the bias voltage.
30. The image-forming apparatus of item 26, wherein the cleaning apparatus comprises: a control section to control the constant current source so as to apply either the toner-collecting voltage or a toner-releasing voltage onto the cleaning roller by selecting one of them in a time-sharing manner, wherein both the toner-collecting voltage and the toner-releasing voltage are equivalent to the bias voltage.
31. The image-forming apparatus of item 29, wherein the control section controls the constant current source so as to apply either the toner-collecting voltage or a toner-releasing voltage onto the cleaning roller by selecting one of them in a time-sharing manner, wherein both the toner-collecting voltage and the toner-releasing voltage are equivalent to the bias voltage.
32. The image-forming apparatus of item 26, wherein the constant current source starts applying the bias voltage onto the cleaning roller after the image bearing member started moving and after a developing bias voltage has been applied onto the developing device, and further, the constant current source stops applying the bias voltage onto the cleaning roller before the image bearing member stops moving and before an operation of applying the developing bias voltage onto the developing device is finished.
33. The image-forming apparatus of item 26, wherein dimension W1 (mm), which indicates a width of the cleaning roller in its longitudinal direction, dimension W2 (mm), which indicates a width of a developer feeding device employed for the developing device in its longitudinal direction, and dimension W3 (mm), which indicates a width of the photosensitive layer on the image bearing member, fulfill a relational expression of
W2 less than W1 less than W3. 
34. The image-forming apparatus of item 26, wherein the constant current source applies the bias voltage onto the cleaning roller so that a toner deposit amount per unit area on a surface of the image bearing member is not greater than 0.25 mg/cm2 at a surface area at which the image bearing member contacts the cleaning roller.
35. The image-forming apparatus of item 26, wherein an average circularity of toner particles included in the toner is within a range of 0.96 to 0.99, and a mass average particle size of the toner particles is within a range of 3 to 10 microns.
36. The image-forming apparatus of item 34, wherein a fur brushing roller is employed for the cleaning roller.
37. An image-forming apparatus, comprising: a first image bearing member: a plurality of developing devices arranged around a periphery of the first image bearing member; a second image bearing member on which a toner image formed on the first image bearing member is temporarily transferred; the cleaning apparatus cited in item 1, the cleaning apparatus being equipped for either the first image bearing member or the second image bearing member.
Further, to overcome the abovementioned problems, other cleaning systems, cleaning apparatus and cleaning methods, embodied in the present invention, will be described as follow:
a1. A cleaning system characterized by comprising: a conductive or semiconductive cleaning roller in contact with an image bearing member carrying the charged toner; a constant current source from which bias voltage having a polarity reverse to that of the toner related to development on said image bearing member is applied to said cleaning roller; and a cleaning blade contacting said image bearing member at the downward position in the movement of said image bearing member.
a2. A cleaning system according to item a1 characterized in that the contact surface of said cleaning roller rotates to move in the same direction as said image bearing member at the position in contact with said image bearing member, and the ratio between the traveling speed of the cleaning roller at the contact face and that of said image bearing member at the contact face and is in the range from 0.5:1 to 2:1.
a3. A cleaning system according to item a1 or a2 characterized by comprising a means of removing toner from said cleaning roller by contacting said cleaning roller.
a4. A cleaning system according to item a1 characterized in that said cleaning blade is brought in contact with said image bearing member at the load from 1 to 30 grams/cm.
a5. A cleaning system according to any one of items a1 to a4 characterized in that the contact angle between said image bearing member and said cleaning blade is within the range from 0 to 40 deg.
a6. A cleaning system according to any one of items a1 to a5 characterized in that the hardness of said cleaning blade is within the range from 20 to 90 deg.
a7. A cleaning system characterized by comprising: a conductive or semiconductive cleaning roller in contact with an image bearing member carrying the charged toner; a constant current source from which bias voltage having a polarity reverse to that of the toner related to development on said image bearing member is applied to said cleaning roller; a control means of controlling said constant current source; and a cleaning blade located at the downward position in the movement of said image bearing member, with said cleaning blade contacting said image bearing member; wherein said control means is characterized by controlling said constant current source so that said constant current source applies the current whose absolute value is changed according to the increase in the amount of the image formed.
a8. A cleaning system according to item a7 characterized in that the amount of the image formed is equivalent to the number of sheets for formed image.
a9. An image forming system comprising an image bearing member and a cleaning system according to any one of items a1 to a8.
a10. An image forming system according to item a9 characterized in that said image bearing member is an organic photoconductor.
a11. An image forming system according to item a9 or a10 characterized by comprising a development device wherein development is performed by using the toner whose particles are formed by polymerization method, with the volume mean particle size ranging from 3.0 to 8.5 microns.
b1. A cleaning system characterized by comprising: a conductive or semiconductive cleaning roller in contact with an image bearing member carrying the charged toner; a electronic-power source to apply toner-collecting voltage to said cleaning roller; a control means of controlling said electronic-power source; and a cleaning blade located downward of said cleaning roller in the direction of said image bearing member movement, with said cleaning blade contacting said image bearing member; wherein said control means is characterized by controlling said electronic-power source so that said toner-collecting voltage whose absolute value is changed according to the increase in the amount of the image formed is applied to said cleaning roller.
b2. A cleaning system according to item b1 characterized in that wherein the amount of the image formed is equivalent to the amount of the image formed.
b3. A cleaning system characterized by comprising: a conductive or semiconductive cleaning roller in contact with an image bearing member carrying the charged toner; a electronic-power source to apply toner-collecting voltage and toner-releasing voltage to said cleaning roller; a control means of controlling said electronic-power source; and a cleaning blade located downward of said cleaning roller in the direction of said image bearing member movement, with said cleaning blade contacting said image bearing member; wherein said control means is characterized by controlling said electronic-power source so that said toner-collecting voltage and said toner-releasing voltage are applied selectively in terms of time.
b4. A cleaning system according to item b3 further characterized in that said tone discharge voltage is applied at every formation of the image in specified numbers of sheets.
b5. A cleaning system according to item b4 further characterized in that said toner-releasing voltage is applied at every formation of the image in said specified of sheets which changes according to the number of sheets for formed image.
b6. A cleaning system according to any one of items b3 to b5 further characterized in that said toner-releasing voltage is composed of alternate current voltage (hereinafter, referred to as a.c. voltage) superimposed on direct current voltage (hereinafter, referred to as d.c. voltage).
b7. A cleaning system characterized by comprising: a conductive or semiconductive cleaning roller in contact with an image bearing member carrying the charged toner; a electronic-power source to apply toner-collecting voltage and toner-releasing voltage to said cleaning roller; a control means of controlling said electronic-power source; and a cleaning blade located downward of said cleaning roller in the direction of said image bearing member movement, with said cleaning blade contacting said image bearing member; wherein said control means is characterized by controlling said electronic-power source so that said recovery voltage whose absolute value is increased according to the amount of the image formed is applied, and said toner-collecting voltage and said toner-releasing voltage are applied selectively in terms of time.
b8. A cleaning system according to item b7 further characterized in that the amount of the image formed is equivalent to the number of sheets for formed image.
b9. A cleaning system according to item b7 or b8 further characterized in that said toner-releasing voltage is applied at every formation of the image in specified numbers of sheets.
b10. A cleaning system according to item b9 further characterized in that said toner-releasing voltage is applied at every formation of the image in said specified of sheets which changes according to the number of sheets for formed image.
b11. A cleaning system according to any one of items b7 to b10 further characterized in that said toner-releasing voltage is composed of a.c. voltage superimposed on d.c. voltage.
b12. A cleaning system according to any one of items b1 to b11 characterized in that the contact surface of said cleaning roller rotates to move in the same direction as said image bearing member at the position in contact with said image bearing member, and the ratio between the traveling speed of the cleaning roller at the contact face and that of said image bearing member at the contact face and is in the range from 0.5:1 to 2:1.
b13. A cleaning system according to any one of items b1 to b12 characterized by comprising a means of removing toner from said cleaning roller by contacting said cleaning roller.
b14. A cleaning system according to any one of items b1 to b13 characterized in that said cleaning blade is brought in contact with said image bearing member at the load from 1 to 30 grams/cm.
b15. A cleaning system according to any one of items b1 to b14 characterized in that the contact angle between said image bearing member and said cleaning blade is within the range from 0 to 40 deg.
b16. A cleaning system according to any one of items b1 to b15 characterized in that the hardness of said cleaning blade is within the range from 20 to 90 deg.
b17. An image forming system comprising an image bearing member and a cleaning system according to any one of items b1 to b16.
b18. An image forming system according to item b17 wherein said image bearing member is an organic photoconductor, said image forming system further characterized by comprising: a charging device to charge said organic photoconductor; an exposure device to expose said charged organic photoconductor; and a development device to form an image by developing the electrostatic latent image formed on said organic photoconductor by charging and exposure, and by depositing the charged toner thereon.
b19. An image forming system according to item b18 characterized in that development is performed by using the toner whose particles are formed by polymerization method, with the volume mean particle size ranging from 3.0 to 8.5 microns.
c1. An image forming system comprising: an image former having a photosensitive layer on the surface thereof, a development device by making latent image on said image former visible by means of toner; a transfer device to transfer a toner image on said image former to the transfer image bearing member; and a cleaning system to remove toner from the image former after transfer; said cleaning system further characterized by comprising at least; a cleaning roller which is located in contact with image former, rubs the image former surface and consists of a conductive or semiconductive elastic body; a cleaning blade consisting of an elastic body located downward of said cleaning roller in the direction of image former movement; and a electronic-power source to apply bias potential to said cleaning roller; wherein application of bias potential from said electronic-power source starts later than start of said image former movement or application of bias potential to said development device, and terminates later than termination of application of bias potential to said development device, and earlier than suspension of said image former movement.
c2. An image forming system according to item c1 characterized in that said electronic-power source is a constant current source.
c3. An image forming system according to item c1 or c2 characterized in that the toner making said latent image visible is synthesized by polymerization, and has a volume mean particle size ranging from 3.0 to 8.5 microns.
c4. An image forming system comprising: an image former having a photosensitive layer on the surface thereof; a development device by making latent image on said image former visible by means of toner; a transfer device to transfer a toner image on said image former to the transfer image bearing member; and a cleaning system to remove toner from the image former after transfer; said cleaning system further characterized by comprising at least; a cleaning roller which is located in contact with image former, rubs the image former surface and consists of a conductive or semiconductive elastic body; a cleaning blade consisting of an elastic body located downward of said cleaning roller in the direction of image former movement; and an electronic-power source to apply bias potential to said cleaning roller; said image forming system further characterized in that
W2 less than W1 less than W3, 
xe2x80x83Where, W1: width of said cleaning roller in the longitudinal direction (mm), W2: width of developer feed in the longitudinal direction in said development device (mm), and W3: width of the photosensitive layer on said image developer in the longitudinal direction (mm).
c5. An image forming system according to item c4 characterized in that said electronic-power source is a constant current source.
c6. An image forming system according to item c4 or c5 characterized in that the toner making said latent image visible is synthesized by polymerization, and has a volume mean particle size ranging from 3.0 to 8.5 microns.
d1. An image forming method characterized in that; a mean circularity of the toner used for image formation is 0.96 to 0.99; a cleaning blade rubbing an image bearing member in contact therewith, and a toner recovery means installed on the upstream side of said cleaning blade are provided to remove the remaining toner deposited on the image bearing member after toner transfer; and cleaning is carried out when the deposit amount per unit area of toner on the image bearing member which reaches said cleaning blade after passing through said toner recovery means is smaller than 0.25 mg/cm2.
d2. An image forming system wherein a toner image is formed on a rotating carrier, and toner remaining after having been transferred by a transfer means is cleaned by a cleaning system; said image forming system comprising a cleaning blade contacting and rubbing said image bearing member elastically and a toner recovery means located on the upstream side of said cleaning blade; said image forming system further characterized in that the bias voltage having a polarity reverse to the charging characteristics of toner is applied to said toner recovery means, and the deposit amount per unit area of passing toner is smaller than 0.25 mg/cm2.
Said image forming system is preferred to use the toner having a mean circularity ranging from 0.96 to 0.99 and a weight mean particle size ranging from 3 to 10 microns. The present invention provides an image forming system which ensures formation of high quality image by excellent cleaning through the use of said toner.
e1. A cleaning system for cleaning an image bearing member to form images using toner with a high mean circularity of 0.96 or more, said cleaning system comprising: a cleaning blade for cleaning with its end in contact with said image bearing member; a cleaning roller located on the upstream side of said blade with said roller cleaning said image bearing member in contact with it; and a bias voltage application means for applying bias voltage to said cleaning roller.
e2. A cleaning system according to item e1 wherein said cleaning roller is a conductive elastic roller.
e3. A cleaning system according to item e1 or e2 comprising a control means for application of bias voltage by said bias voltage application means through d.c. constant current control.
e4. An image forming system comprising a cleaning system according to item e2 or e3.
e5. An image forming system comprising a cleaning system according to any one of items e1 to e3 characterized in that multiple development means are installed around the first image bearing member, a toner image formed on said first image bearing member is primarily transferred onto the second image bearing member, and the toner image on the secondary image bearing member having been primarily transferred in the above step is secondarily transferred onto a recording medium; wherein the cleaning system of said first image bearing member or said second image bearing member is the cleaning system according to any one of items e1 to e3.
e6. An image forming method comprising: a development process for forming images in the image bearing member using toner with a high mean circularity of 0.96 or more; a transfer step for transferring a toner image on said image bearing member; and a cleaning step for cleaning said image bearing member subsequent to said transfer step; said cleaning process further characterized in that the tip of the cleaning blade is brought in contact with said image bearing member to perform cleaning after a cleaning roller with bias voltage applied thereto is bought in contact with the image bearing member to perform cleaning.
e7. An image forming method according to item e6 characterized in that said cleaning roller is a conductive elastic roller.
e8. An image forming method according to item e6 or e7 characterized in that bias voltage is applied to said cleaning roller through d.c. constant current control.